1. Field of the Invention
The present invention relates to a method and apparatus for storing a cargo container chassis when it is not in use. More particularly, the invention concerns tilting the cargo container chassis to a raised position in which it can be stored while occupying a minimum amount of space.
2. General Description of the Background
Truck drawn cargo container trailer chassis are used to transport goods in large, detachable shipping containers. The containers are detached from the chassis at a railway or seaport terminus, where the containers and goods may then be shipped by rail or boat in the container. A large number of empty trailer chassis must then be stored at or near ship and rail terminals when the chassis are not in use. Storing such a large number of chassis is a problem because they are large and obtrusive. They obstruct the free flow of traffic and occupy often valuable land near seaports and other congested areas. In addition to occupying valuable space, the chassis may also be damaged or stolen while stored.
It has been suggested that a chassis may be stored most efficiently in an upright position in storage racks, such as the storage racks shown in U.S. Pat. No. 4,549,663 and U.S. Pat. No. 4,493,421. One problem with these storage methods, however, is that the chassis must be clamped by a specially designed clamping apparatus which is attached to a lift truck. Examples of such specially designed clamping mechanisms are shown in U.S. Pat. No. 4,437,807, U.S. Pat. No. 4,583,902 and U.S. Pat. No. 4,600,350.
The use of such clamps presents several significant problems. The clamps themselves must firmly engage the heavy chassis to rotate it from a horizontal to a vertical position. The clamps must also exert significant compressive or frictional force against the heavy chassis to rotate it, and such forces can damage a light weight chassis, particularly after repeated applications. Moreover, the clamping attachment is an expensive, unwieldy piece of equipment that increases the cost of the storage operation.
Yet another problem with these previous systems is that cargo container chassis are becoming longer and often heavier. The economics of transporting goods dictates that ever greater amounts and weights of materials be transported at a single time. In some cases they may merely be made longer, but of the same or lighter materials and thus do not have the higher beam strength of prior devices. The longer and heavier, or possibly longer and more flimsy chassis are therefore more difficult to lift, often requiring greater clamping forces. Moreover, the transport vehicles which clamp the chassis must also be made larger and heavier to counteract the increased weight of the chassis that is being manipulated. Finally, it is expensive and difficult to manufacture tiltable booms that can raise such a heavy chassis to a vertical orientation. The weight of the boom, attached clamp and heavy chassis requires extraordinarily durable and expensive hydraulic lifts to move the boom and the attached trailer.
It is therefore an object of this invention to provide a system and method for storing a cargo container chassis, but which avoids the necessity of clamping and possibly damaging the chassis.
It is yet another object of the invention to provide a means for lifting a heavy chassis without the necessity of making a heavier and correspondingly more expensive lift and transport vehicle.
Yet another object of the invention is to provide such a method and mechanism that can economically and efficiently raise a variety of different kinds of chassis to a generally vertical position in which the chassis is transported to a storage structure and stored.